Hi Salma,
My understanding is that for rows having GDALT in range 200-400 you would like to find the row where NE8 is maximum.
Please see if this code helps
txt = readtable("table.txt");
% I'm adding an Index Column, in case you specifically want the index
txt.INDEX = (1:height(txt))';
subTable = txt(txt.GDALT >=200 & txt.GDALT <=400, :);
% getting idx in the subtable using max function
[~,idx] = max(subTable.NE8,[],'omitnan');
% this row contains the required result. You can use the index from this
% row.
result = subTable(idx,:)
Hope this helps.
